The invention relates to the modular avionics equipment items embedded on aircraft such as, for example, airplanes, and more particularly the cooling of electronic circuit boards in such avionics equipment items.
In the field of embedded electronics, and in particular on aircraft, the modular electronics designs aim to reduce the maintenance costs and increase the availability of the applications. An avionics module is, within the terms of the following description, an electronics subassembly which, by virtue of a suitable mechanical interface and connection system, can be installed on the aircraft and be uninstalled individually therefrom according to the needs of maintenance, troubleshooting, upgrading, etc. of the embedded avionics.
It is a proven fact that the trend of the technologies in the electronics world has led to an increase in the power densities dissipated in the electronic components. This trend makes it necessary to ensure appropriate cooling of the electronic circuit boards in order to guarantee the operation of the electronic avionics functions.
An avionics equipment item can be made up of avionics modules each comprising a removable housing enclosing a certain number of electronic circuit boards that cannot be extracted in situ from the housing and that are not streamlined (equipment of ARINC 600 type). The housing is fixed on a main air stream for cooling the equipment item and the distribution of the air to the electronic circuit boards is performed globally inside the housing. The flow of air is thus diffused in the equipment, without differentiation onto the front face (so-called “TOP” face) and the rear face (so-called “BOTTOM” face) of the circuit boards that it contains. As a general rule, the heat-dissipating components are combined on one of the two faces of the electronic circuit boards, generally the front face. If there is not enough surface area on the front face, the rear face can be used for mounting certain components, whether heat-dissipating or not. Because of its global distribution, the cooling air flow is not therefore used optimally for the cooling of the circuit boards in the housing.
Now, because of increasing thermal powers to be dissipated on/in the electronics embedded in the aircraft, it is crucial to optimize the cooling of these electronics.
This problem arises also in the case where, instead of handling avionics modules each containing a number of electronic circuit boards, there is a tendency to handle the electronic circuit boards individually. With such an arrangement, each electronic circuit board is streamlined, which means that it is individually received in a case or sheath provided with an appropriate connection system to form an avionics module (also called “blade”).
The avionics modules with individual electronic circuit board of this second type are received in groups in an avionics equipment item designed to allocate each avionics module a given air flow rate which is used to ventilate the electronic circuit board inside its case.
The invention aims to provide an avionics module of the abovementioned second type which makes it possible to optimize the cooling of the electronic circuit board positioned inside this module.